Progress in direct-drive inertial confinement fusion at the Laboratory for Laser Energetics

Summary form only given, as follows. Direct-drive inertial confinement fusion (ICF) offers the potential for high gain and is a leading candidate for an inertial fusion-energy power plant. Laser and target nonuniformities can seed hydrodynamic instabilities during the implosion that, in turn, can compromise target performance. This is the primary target physics issue for direct-drive ICF. Several methods have been devised to control these seeds and their subsequent growth, including laser beam smoothing, advanced pulse shaping, target design, etc. LLE's baseline direct-drive ignition design for the National Ignition Facility (presently under construction at the Lawrence Livermore National Laboratory) is composed of a thin plastic shell enclosing a thick deuterium-tritium layer. It provides a gain of 45 in spherically symmetric calculations (30 in two-dimensional simulations which include the effects of laser and target nonuniformities). Recent improvements to the ignition target design include the addition of a picket to the beginning of the laser pulse shape that reduces both the seeds and growth rate of the hydrodynamic instabilities.